In general, a polar relay comprises an insulation housing, a coil assembly accommodated within the insulation housing, an armature assembly, and a plurality of groups of contact assemblies. The coil assembly comprises a coil and an iron core. In the prior art, a coil is typically mounted into an insulation base of the insulation housing in a top-down installation manner, and the iron core is inserted into the coil.
Nowadays, a commercially available polar relay is typically arranged in a form of an I-shaped magnetic circuit configuration, with one end of the iron core functioning as a pivot point and the other end of the iron core being pivotable around the pivot point. With such magnetic circuit configuration, firstly, it is necessary to provide a magnetic isolation plate between the armature and the iron core, or to apply an isolation layer onto contact layers between the armature and the iron core when this magnetic circuit configuration is used for a monostable product. A magnetic isolation plate or an isolation layer prevents a resultant electromagnetic force from increasing steeply and hence ensures a normal release of the product, but leads to a higher cost. Secondly, it is possible that a position of the pivot point is changed during movement of the iron core, resulting in a non-continuous course of action of the relay product.